ES2645297B1 - FILM OF POLYMER MATERIAL WITH THERMO-PHOTOCROMIC PROPERTIES FOR COLOR REGULATION OF GLASSED SURFACES AND PLASTIC MATERIALS - Google Patents

Abstract

Polymeric material film with thermo-photochromic properties for color regulation of glazed surfaces and plastic materials. # The invention relates to a polymeric material film with thermo-photochromic properties comprising micrometric and / or nanometric size capsules embedded and deposited of homogeneously dispersed in its structure, said capsules being formed by a solid wall of a polymer different from the polymer of the film which contains in its interior a dispersion of at least one photochromic compound of type T that is selected within the group consisting of spiropyrans , spiroxacins, chromenes and any combination thereof, in a liquid phase change material of non-volatile acid type that interacts with the photochromium as a function of temperature. This film, thanks to its properties, has multiple uses as a surface coating material to which it is desired to confer photochromic color change properties, such as blackboards, device screens, advertising surfaces, vehicles and glass or plastic surfaces in general.

Description

5

10

fifteen

twenty

25

30

35

DESCRIPTION

FILM OF POLYMER MATERIAL WITH THERMO PROPERTIES

PHOTOCROMICS FOR COLOR REGULATION OF GLASSED SURFACES AND PLASTIC MATERIALS

Object and technical sector of the invention

The invention refers to a polymeric film or polymer film of the type used in places where protection from sunlight / natural light is required, for the manufacture of memory devices by photo-thermochromic effect and screens / blackboards in which the image is produced by a laser pointer of visible light.

Background of the invention

Photochromic materials are used in those applications in which you want to regulate the amount of light that crosses a certain surface. Some examples are photochromic glasses and smart windows. In these applications, the photochromic layer is colored (darkened) when it is crossed by ultraviolet light, acting as a filter for visible radiation. In the absence of UV radiation, the photochromic layer spontaneously returns by thermal reaction to the non-colored transparent state. This process is reversible and is defined as direct or positive photochromism. On the other hand, there are systems in which the photochrome is in the dark colored state and discolors in the presence of solar radiation (visible component). This process is defined as reverse or negative photochromism. Negative photochromism can be used primarily for memory devices, recording and information and data storage systems. Direct photochromism is generally achieved by dispersing the photochromic molecules in matrices or non-polar solvents. Polymeric matrices such as polymethylmethacrylate, polycarbonates, polystyrenes and the like, commonly used in applications with photochromes (glasses, helmet visors, etc.) have direct photochromism. On the other hand, in silica gel or polysiloxanes with a low percentage of organic phase, in acidic or very polar solvents and in systems capable of forming complexes (metals) with the phenoxide group of the merocyanin species of the photochrome, reverse photochromism is favored. In short, the matrices in which the photochromes are dispersed generally favor either direct photochromism or reverse photochromism. In some systems, such as polysiloxanes or silica gels with high organic phase content, they can simultaneously present reverse and direct photochromism according to the wavelength at

5

10

fifteen

twenty

25

30

They are irradiated. However, in these systems a reversible interconversion (switching) of direct to reverse photochromism cannot be obtained, and the two types of photochromism compete with each other (J. Phys. Chem. 1988, 92, 4734; Chem. Soc Rev., 2011, 40, 672; Chem. Abstr. 1970, 72, 127256; J. Mater. Chem, 1997, 7, 61; J. Phys. Chem., 1996, 100, 9024). The silica gel matrices, therefore, can be prepared so that the same photochromic molecule has direct or reverse photochromism. However, the interconversion discussed above is not possible in these systems. Another system that allows the same photochromic molecule to present, under different conditions, direct or reverse photochromism, is based on the presence or absence of a complexing agent, such as metals (Dyes and Pigments, 2008, 76, 832; J. Org. Chem. 2002, 67, 2223; J. Org. Chem, 2001, 66; J. Phys. Chem. B 2004, 108, 11942; J. Photochem. & Photobi. A: Chemistry, 2011, 222, 236), of the merocyanin form of the photochromes. In the absence of the complexing agent, the system presents direct photochromism, while in its presence reverse photochromism occurs. With this system the photochromic can go from direct to reverse photochromism simply by adding the complexing agent. However, to return to direct photochromism it is necessary to eliminate the complexing agent from the system, which implies using separation and purification techniques. In addition, it should be noted that the system is described only in the liquid phase, which would not allow the preparation of a polymeric film such as that described in the present invention.

A fully reversible interconversion between direct and reverse photochromism has been described in dissolution of photochromes in volatile solvents or in aqueous solution, where the variation of pH by adding an acid or a base stabilizes the colored or colorless form, respectively, of the photochrome giving rise to reverse or direct photochromism (J. Am. Chem. Soc. 2001, 123, 4651, Chem. Lett. 2014, 43, 281; J. Photochem. & Photob. A: Chemistry, 2007, 191, 114). Similarly to the previous case, this system has been described only in solution and with solvents / volatile acids, therefore it could not be used as a polymeric film for devices that have reverse or direct photochromism as needed. In addition, the change in photochromism is obtained each time by adding the components that induce a change in the pH (acid or bases) of the medium. This would lead to an accumulation of material in the photochromic system and would be incompatible with its use as a device based on a polymeric film.

5

10

fifteen

twenty

25

30

35

In patent application EP1473592 A1 a system is described where films composed of polymeric microcapsules containing an acid with a P-type photochrome are used to retain (keeping the acid contained in the capsules in solid form) or not (melting the acid) the color of the photochrome in the presence of visible radiation. This system has been developed for the generation of images on screens. The phase change of the acid contained in the microcapsules only favors or disadvantages the discoloration of the photochrome under visible light radiation.

In the present technology, the film or film bases the change of photochromism on a reversible change of pH. This change in pH is achieved simply by melting or solidifying the acid contained in the photochrome molecule inside the capsules. This process is obtained by a temperature change around the melting point of the phase change material and does not require the addition of external agents such as complexing agents, acids or bases. When the acid phase change material is below its melting point, the photochrome is in a solid matrix in which acid-base reactions cannot take place. The stable isomer of the photochrome corresponds to the spirn, closed and colorless form. By subjecting the system to ultraviolet radiation, the photochrome is colored to form the colored merocyanin metastable species that, when radiation ceases, discolors forming the colorless species. Upon reaching the melting temperature of the phase change material, the acid melts and interacts with the photochrome by transferring the proton and thus stabilizing the open, merocyaninic and colored form of the photochrome. Under these conditions, when irradiating with visible light, the photochrome discolors generating the closed and colorless metastable species, which ceases to form the colored species when the radiation ceases. This ensures that the device can reversibly show reverse or direct photochromism without addition or accumulation of external material.

In the present invention, the phase change of the acid solvent contained in the photochromic capsules, as a consequence of a temperature variation, induces the reversible formation / disappearance of the color of the photochrome (thermochromic property). In addition, depending on the state of the photochrome (colored / discolored) the system can be subjected to specific radiation to achieve reverse or direct photochromism. The interconversion to move from direct to reverse photochromism and vice versa is achieved by a temperature change and since the interconversion generates a color change the film also has thermochromic properties.

5

10

fifteen

twenty

25

30

35

Description of the invention

The present invention relates to a polymeric film or film of a surface coating polymer with photochromic properties, comprising micrometric and / or nanometric size capsules embedded and deposited in a homogeneously dispersed structure, said capsules being formed by a wall solid polymer different from the polymer of the film that contains in its interior a dispersion of at least one T-type photochromic compound, selected from the group consisting of spiropyranos, spiroxacin, chromen and any combination thereof, in a liquid exchange material Non-volatile acid type phase, which interacts with the photochromium as a function of temperature.

As an acid-type phase change material, in this precise application it is understood that a material can have two different phases interchangeable by temperature and that the liquid phase (obtained above its melting point) acts as an acid. This definition includes the following means: aliphatic carboxylic acids, phosphonic acids, non-volatile alcohols, phenols and polyalkylsiloxanes with hydroxyl groups at their terminations.

Micrometric size capsules should be understood as those that have an average size between 101 nm and 1000 microns, including both limits, while nano-sized capsules are those that have an average size between 10 and 100 nanometers, including both limits .

The bark or wall of the capsules can be of any organic or inorganic polymeric material. Examples of organic polymers for the bark are polystyrene, polyamines, polyureas, polyurethanes, polymethylmethacrylate (PMMA) or polysulfones (PES), among others, although the possibilities are not limited to these polymers. The inorganic cortices could be made by silica gel obtained by the polymerization of tetraalkyl orthosilicate monomers. In the most preferred cases, the bark or wall of the capsules is made of polymethylmethacrylate (PMMA) or polysulfones (PES).

As mentioned, the photochromes required for this technology are selected from the group formed by the family of spiropyranos and / or spiroxacin and / or chromen. That is, the photochromes can be used individually or in combination.

5

10

fifteen

twenty

25

30

35

to get a defined resulting color. The photochromes of the spiropyran family may preferably be selected from the group consisting of 1 '- (2- hydroxyethyl) -3', 3'-dimethyl-6-nitro-spiro [1 (2H) - benzopyran-2,2 ' -indoline], 1 ', 3', 3'-Trimethyl-6- nitrospiro [1 (2H) - benzopyran-2,2'-indoline], 1 ', 3', 3'-Trimethylspiro [1 (2H) - benzopyran-2,2'-indoline] and 8-Methoxy-1 ', 3', 3'-trimetillspiro [1 (2H) -benzopyran-2,2'-indoline]; while the photochromes of the spiroxacin family can preferably be selected from 1,3,3-trimethylspiro [2H-indole2,3 '- [3H] naphtho [2,1-b] [1,4] oxacin] and 1 , 3,3-

trimethylspiro [2H-indole-2,3 '- [3H] phenanthro [9,10-b] (1,4) oxacin].

The liquid phase change material, also called to abbreviate in this memory half acid, contained in the capsule, in which the photochromes are dispersed and which allows the formation of color within the capsules when interacting with them, is selected within the group consisting of aliphatic carboxylic acids, phosphonic acids, phenols, non-volatile alcohols and alternatively polyalkylsiloxane that end with hydroxyl groups. As the acid, an acid with a carbon number greater than 7 can be used, that is to say selected from the group consisting of heptanoic, octanoic, nonanoic, decanic, undecanoic, dodecanoic acid and any acid with a carbon number greater than 12. They could also be used Phosphonic acids such as those selected from the group consisting of decyl phosphonic acid, dodecyl phosphonic acid, hexadecyl phosphonic acid and octadecyl phosphonic acid. As non-volatile alcohol, any alcohol with a carbon number greater than 8 can be used, ie 1-nonanol, 1-decanol, 1-undecanol and any alcohol with a carbon number greater than 11. As polyalkylsiloxanes, those having terminations can be used of hydroxides such as poly (dimethyl-co-diphenylsiloxane) with hydroxide group at its terminations.

The melting point of the acid medium in which the photochromes are dispersed is key to achieving one type of photochromism or another (positive or negative). Thus, preferably, the melting point of the acid solvent medium is between -15 ° C (which is the lowest, corresponding to 1-octanol) and 95 ° C (the highest, shown for example by octadecyl acid phosphonic), temperature below which the positive photochromism is achieved and above it the negative photochromism; In general, the melting point of the acid solvent medium establishes the temperature of interconversion between direct and reverse photocromism.

5

10

fifteen

twenty

25

30

35

The acidic medium, in its liquid phase, interacts with the photochrome by means of a proton transfer to it, which, once received this proton, isomerizes towards the open, protonated, colored merocyaninic form that becomes the most stable form. When the acidic medium is in the solid phase (below its melting point), it only acts as a matrix for the photochrome which, due to the lack of proton transfer, maintains the closed and colorless isomer as stable. That is, the acidic medium, above its melting point, is in a liquid state and interacts with the photochrome, and that below its melting point is in a solid state and acts as a matrix of the photochrome, without chemically interacting with the same. Thus, in this application, the acidic medium is any material that produces this reversible change of the stable species of the photochrome by the presence or absence of proton transfer.

In a preferred embodiment, in which reverse photochromism above ambient temperature and direct photochromism below ambient temperature is required, (understood as ambient temperature as that between 25 ° C - 30 ° C), it can be used as a solvent medium an acid that once molten generates color formation and allows reverse photochromism. Preferably for this embodiment, the acidic media selected are dodecanoic acid and octadecyl phosphonic acid, which have a melting temperature of 43 ° C and 95 ° C, respectively.

In another preferred embodiment, an acid with a melting temperature below room temperature can be used as the solvent medium, which allows films to be obtained, at room temperature, directly reverse photochromism without requiring the use of temperature as a stimulus. As a preferred system, the acidic medium selected to achieve a film that exhibits reverse photochromism at room temperature is nonanoic acid (melting point of 13 ° C).

This liquid material in which the photochromes are dispersed and which is contained within the capsules does not react in any way with the wall of said capsules.

The film of interest may be formed by a polymer selected from the group consisting of polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), ethyl cellulose, polymethylmethacrylate, polystyrene, acrylic, styrenic, polyurethane, polyurea and polyamide. The use of one or another polymer for film formation will determine

5

10

fifteen

twenty

25

30

35

the method of obtaining it. Thus, in a particular embodiment of the invention, said polymeric film containing the capsules can be prepared by dropcasting, spin-coating or dip-coating from the preparation of a suspension of the capsules in a solvent containing the polymer that will generate the film. As a solvent in the process, water or any other volatile organic solvent can be used that does not damage the capsules and at the same time is capable of dissolving the polymer that will generate the film. For example, using the dropcasting technique, the aqueous suspension of capsules with PVA (water soluble) is deposited on a flat surface or in a container and the water is allowed to evaporate at room temperature or slightly above room temperature (40 ° C - 50 ° C). As the water evaporates, the polymer precipitates by trapping the capsules contained in the initial suspension.

Alternatively, in another particular embodiment of the invention, the film can be prepared by in-situ polymerization of monomer suspensions containing the capsules. Thus, during polymerization, the capsules would be trapped in the final polymer. Thus, polyacrylic, polystyrene, polyurethane, polyurea, polyamide (Nylon) films can be generated from the corresponding monomers: acrylates, styrenes, polyols with polyisocyanates, polyamines with polyisocyanates, polyamines with acyl polychlorides.

The generated polymeric film can thus remain as a coating of the surface on which the suspension has been deposited to form the film with the capsules.

It may be convenient to apply a protective film on one of the two faces of the photochromic film, said protective film being formed by an acrylic, styrenic, polyamide, polyurethane or glass material. Alternatively, the film can be used as a polymeric material to produce laminates with photochromic properties by entrapment between two transparent plastic or glass sheets, such that the invention covers a structure formed by two transparent glass or plastic sheets comprising between them. the polymeric material film with photo-thermochromic properties. However, in its most common configuration, this film can be used to regulate the transparency of glazed surfaces and plastic materials, and thus can be used as polymeric material in devices of the protective glass type.

5

10

fifteen

twenty

25

30

35

The preferred method of synthesis of micrometric and nanometric size capsules is a solvent evaporation process that has the advantage of the absence of chemical reactions during the synthesis process and reduces the risk of modifying the functional groups of the photochromic molecules. The method begins with the preparation of an emulsion from an organic phase and an aqueous phase, the organic phase being composed of a polymer (for example, PMMA or PES), a photochrome, a volatile organic solvent (of lower boiling temperature 100 ° C) not miscible with water (preferably dichloromethane or chloroform) and a high boiling acid medium (greater than 150 ° C) necessary for the generation of color. The aqueous phase is in turn composed of water and a surfactant that stabilizes the emulsion. The surfactant can be anionic (for example, sodium dodecyl sulfate), cationic or neutral (Tween®, polyvinyl alcohol, polyvinyl pyrrolidone) and in an amount by weight of 0.1-2% with respect to the aqueous phase. Thus, the emulsion is prepared by mixing the organic phase with the aqueous phase and emulsifying by magnetic stirring or with shear emulsifier (Ultra Turrax®) or ultrasound. Once the emulsion is produced, the volatile solvent is evaporated and the precipitation of the polymer around the acid drops is induced, forming the corresponding capsules.

Thus, the method of synthesis used is characterized by the absence of chemical reactions in the process, and the photochromes, acidic media and polymers for synthesis, both of the capsules and of the films used, are commercially available, so a previous synthetic modification of them is not necessary. In the case of films prepared from monomers, the latter are also commercially available. These factors together make the technology easily scalable.

The film containing the photochromic capsules is shown in schematic form in Figure 1.

In this way, the film acts as a crystalline solid matrix that supports photo-thermochromic capsules, so that they confer their properties on the film itself. Thus, the invention consists of a solid system capable of changing state between two types of photochromism, reversibly, using temperature as a stimulus. Thus, the film contains in its configuration solid polymeric wall capsules that cover an acid-type phase change liquid in which the photochrome of the indicated type is dissolved. Encapsulation with the bark or wall of nature

5

10

fifteen

twenty

25

30

35

polymer protects, insulates and confers functionality and reversibility to the system, so that the photochrome is the molecule that is responsible for generating the desired color and the acidic medium induces the color change of the photochrome and the interconversion of one type of photochromism to another (direct or reverse), reversibly.

As "reversible color change by application of heat" (thermochromism) or "reversible change between two types of photochromism using temperature as a stimulus" the following phenomenon, which is the property acquired by the film due to its configuration and structure, should be understood:

- Below the melting temperature of the acid-type phase change material (for example, below 25 ° C or what has been previously referred to as "below room temperature"), the capsules have a color white (due to the dispersion of the incident light) or transparent (if the capsules are nanometric in size and do not disperse the light) When irradiating the capsules with ultraviolet light (UV, <400 nm), a spot color is observed where the beam is incised (upper part of Figure 2), this color change being an indicator of the change in the state of the photochrome This is because the photochrome, dispersed in the liquid medium and protected within a solid capsule that It is embedded in the polymeric film that acts as a crystalline solid matrix, when it is irradiated with isomerized UV radiation in a spiro, stable, closed form (from the molecular point of view, the photochrome contains a ring in its structure) and colorless to a Merocyaninic form, photoactivated, open (the ring opens and forms a structure with conjugated double bonds) and colored. When the source of irradiation stops, recovery to the colorless stable form occurs spontaneously thermally. This process is defined as positive or direct photochromism and is the known phenomenon for this family of photochromes (T-type photochromes of the spiropyran families, spirooxacin).

- At temperatures above the melting point of the acid-type phase change material (for example, at 60 ° C), the open and colored form of the photochrome becomes the most stable form. As seen in the lower part of Figure 2, the capsules at this temperature have color (the photochromic absorbs in the visible one), and if they are irradiated with visible light, they discolor. In this case, by stopping the source of irradiation, the photochrome tends to return to the most stable form, so in the dark, the system becomes colored again. This process is defined as negative or reverse photochromism.

5

10

fifteen

twenty

25

30

35

In this way, the temperature change intrinsically generates the formation / disappearance of color and therefore the film also acts as a thermochromic film.

In summary, the system that forms the capsules of the acidic medium with the photochromes allows to achieve a film with photochromic properties and, at the same time, a reversible interconversion between positive and negative photochromism using temperature as a stimulus.

Figure 3 shows how the films obtained from the capsules show their behavior, so that they acquire their photochromic property.

In case of using an acid medium with a melting temperature below room temperature, the film would have a reverse photochromism at room temperature. Figure 4 shows this phenomenon of reverse photochromism.

This technology allows either to change the color of the entire surface of the film, or to do it selectively, directed. Thus, it is possible to a) make defined patterns using a UV laser that colors the selected area exposed to the beam (at temperatures below the melting point of the acid-type phase change material) or b) generate patterns with a visible light laser decolouring the acid-type phase-change photochromic system (at temperatures above the melting point of the phase change material). In another specific case, it is also possible to activate the capsule systems by means of non-coherent or directed radiation sources (lamps or the same sun, for example), with which no patterns are achieved but the coloration or discoloration of the total surface of the film. With this light source, masks could be used to discolor or color (depending on the temperature at which it is operated and the wavelength used) certain parts of the device.

Films developed with this technology can give rise to two different types of applications:

- Those applications where reverse photochromism is required. These systems are manufactured from capsules containing acid-like phase change materials with a melting point lower than room temperature.

5

10

fifteen

twenty

25

30

35

(understood as ambient temperature as that between 25 ° C - 30 ° C). Examples are:

o Laminar surface of glass or plastic material intended for shop windows (commercial stores, restaurants) or windows (side and rear) of cars that require transparency during the day and opacity during the night hours, to limit the visibility of the interior. o Laminar surface of glass or plastic material for blackboards / chromic screens that allow to temporarily create images, text or other elements by means of a laser pointer of visible wavelength. The device would initially have a homogeneous color throughout the surface. Using a laser pointer, only the area of interest would be discolored, thus creating images or texts on the device itself. The created image or text would be erased in time thanks to reverse photochromism. The application of temperature or ultraviolet radiation could accelerate the disappearance of the text or image. o Laminated surfaces of glass or plastic material, aimed at the protection of works of art (paintings) or other valuables (books) susceptible to daily radiation. These surfaces would be obscured protecting the object in question until a visitor wants to observe the object. Turning on a light of greater intensity, the discoloration of the protective surface is induced, allowing the view of the object of value or work of art to the visitor.

- Those applications where a reversible interconversion between direct and reverse photochromism is required in response to a change in temperature. These systems are manufactured from capsules containing acid-type phase change materials with a melting point higher than room temperature (understood as room temperature as between 25 ° C - 30 ° C). As examples you can report:

o Coating film for design and fashion oriented textile material (fabrics, buttons ...), which depending on the temperature (above or below the melting temperature of the phase change material), not only give a different color (thermochromic material) but react differently to solar radiation: if the outside temperature is lower than the melting temperature of the phase change material, the system would pass

5

10

fifteen

twenty

25

30

from colorless to color, while if it is superior, the system would change from color to colorless.

o Film covering advertising posters, for outdoor, and traffic signs: up to four different types of text or images could be represented on the same poster according to the environmental conditions (sun and heat, sun and cold, night and heat, night and cold ).

o Coating film for the automotive industry, for example as a body trim.

o Coating film for labels of food products, both food and drink (cans, bottles ...).

o Memory devices, data recording / erasing: combinations of different methods (ultraviolet, visible irradiation, temperature) to generate / eliminate color could lead to several states that can be used for information generation. Since the system is completely reversible, the information can be recorded and deleted for many cycles.

o Films covering documents, bills, etc. aimed at increasing security against counterfeiting. The variety of states that can be achieved through different color change mechanisms, would give the possibility of generating complex and more difficult to reproduce systems for the disclosure of false documents.

Brief description of the figures

- Figure 1: Illustrative scheme of the configuration of the film of polymeric material containing photochromic capsules, in accordance with the present invention. The color of the photochrome (represented here in grayscale) depends on the combination of the state of the phase change material (solid / liquid) and the irradiation wavelength to which the photochrome is subjected.

Elements of figure 1:

1. micro / nanocapsule containing the acid-type phase change material (3), with photochromic (2).

2. Photochrome in the uncolored state.

3. Acid type phase change material in the solid state.

4. polymeric film in the colorless state.

5

10

fifteen

twenty

25

30

35

5. Photochromic in the colored state (due to proton transfer of the molten acid phase change material).

6. acid-phase phase change material in liquid state.

7. Polymeric film in the thermally colored state (thermochromism).

8. Photochrome in the colorless state (due to irradiation with visible light).

9. acid-phase phase change material in liquid state.

10. polymeric film in the colorless state.

11. Photochromic in the colored state (due to irradiation with ultraviolet light).

12. Acid phase change material in solid state.

13. polymeric film in the colored state.

- Figure 2: Schematic representation of the behavior of the photochromic capsules at temperatures below (upper part) and above (lower part) of the melting point of the acid solvent medium, that is at 25 ° C and 60 ° C, respectively, for illustrate the change of state associated with positive (upper) and negative (lower) photochromism.

- Figure 3: Schematic representation of the behavior of the films

Polymers at temperatures below (upper part) and above (lower part) of the melting point of the acid solvent medium, that is at 25 ° C and 60 ° C, respectively, to illustrate the change of state associated with positive (higher photochromism) ) and negative (lower).

- Figure 4: Schematic representation of the behavior of the films

Polymers with capsules containing an acid solvent medium with melting point below room temperature. The film has color and when irradiated with a laser pointer of visible wavelength (532 nm), it fades in the area subject to irradiation.

Examples

Example 1. Preparation of the capsules with 1 '- (2-hydroxyethyl) -3', 3'-dimethyl-6-nitrospiro [1 (2H) -benzopyran-2,2'-indolinal properties with dodecanoic acid and photochromic

thermo-photochromic according to the present invention

For the synthesis of the capsules, a method called solvent evaporation was used. This micro / nanoencapsulation process begins with the formation of an oil-in-water (O / W) emulsion by vigorously mixing an organic phase with an aqueous phase. For the preparation of the organic phase, an amount of the photochrome in question (30mg) was dissolved in 883 mg of dodecanoic acid (phase change material of

5

10

fifteen

twenty

25

30

acid type), at a temperature above its melting point (43 ° C), in the presence of magnetic stirring at 1500 rpm. Then, 500 mg of polymethylmethacrylate was dissolved in 10.4 mL of a volatile organic solvent, the latter being dichloromethane or chloroform, with boiling points of 40 and 60 ° C, respectively. Subsequently, these two solutions were mixed in the presence of magnetic stirring, thus constituting the organic phase. For the preparation of the aqueous phase, 150 mg of surfactant was used, the latter being polyvinyl alcohol (PVA) of medium molecular weight (31000 g / mol) or sodium dodecyl sulfate (SDS); The surfactant was dissolved in 15 mL of distilled water, resulting in a 1% aqueous solution.

The organic solution was poured onto the aqueous solution slowly for 60 seconds under homogenization with an UltraTurrax (R) Ika T18 homogenizer. After an emulsion process for 20 minutes, the solvent was evaporated. For this, the suspension was kept in a bath, at a temperature 5 ° C above the boiling point of the volatile organic solvent, in the presence of high vacuum, for 15 minutes. Subsequently, the capsules obtained were washed by centrifugation for 10 minutes at 12,000 rpm. This process was repeated three times by extracting the aqueous solution and redispersing the precipitate after each wash.

Example 2. Preparation of the capsules of Example 1 with different types of photochromes The same method used in Example 1 was used for encapsulation of other types of photochromic, all commercially available. These can be divided into two known families: spiropyranos and spiroxacin. As regards the first family, the following photochromes were encapsulated separately: 1 ', 3', 3'-trimethylspiro [1 (2H) - benzopyran-2,2'-indoline], 8-Methoxy-1 ', 3 ', 3'-trimethylspiro [1 (2H) - benzopyran-2,2'-indoline] and 1', 3 ', 3'-trimethyl-6-nitrospiro [1 (2H) - benzopyran-2,2'- indoline]. Regarding the second family, they were encapsulated: 1,3,3-trimethylspiro [2H-indole-2,3 '- [3H] naphtho [2,1-b] [1,4] oxacin], 1,3 , 3-trimethylspiro [2H-indole-2,3 '- [3H] phenanthro [9,10-

b] (1,4) oxacin] and two photochromes of commercial name, Reversacol® Athlantic Blue and Velvet Blue.

Example 3. Preparation of a film of polymeric material with thermo-photochromic properties according to the present invention, from the micro and nanocapsules obtained in Examples 1 and 2

5

10

fifteen

twenty

25

30

35

The capsules obtained were dispersed (30 mg) in 7 mL of an aqueous solution, in which 1.4 grams of polyvinyl alcohol (20% PVA solution) had previously dissolved. The suspension was stirred by ultrasound to achieve a homogeneous dispersion. Subsequently, it was deposited in a polystyrene petri dish (4.5 cm in diameter) and the water was evaporated, at room temperature, until the polymer was completely dried by trapping the micro / nanocapsules in its structure.

The film obtained, at room temperature (25-30 ° C) and below the melting point of the encapsulated acid medium (<43 ° C), is discolored, and when irradiating with UV light a color change is observed (passes colorless to magenta), on the part of the surface that has been subjected to radiation. When the radiation is interrupted, the film fades again (direct photochromism). Above 43 ° C, the film is colored (magenta color - thermochromism) and when irradiated with visible light it discolors, recovering its initial color when left in the dark (reverse photochromism).

Example 4. Preparation of the capsules with nonanoic acid and the photochrome 1 '- (2- hydroxyethyl) -3', 3'-dimethyl-6-nitrosoiro [1 (2H) - benzooirane-2,2'-indolinal with thermo properties -photochromes according to the present invention

For the preparation of the capsules the same method used in Example 1 was used. In this particular case, for the preparation of the organic phase, a small amount of the photochrome in question (30mg) was dissolved in 903 mg of nonanoic acid, at room temperature (acid melting point is 13 ° C), in the presence of magnetic stirring at 1500 rpm. Then, 500 mg of polymethylmethacrylate was dissolved in 10.4 mL of a volatile organic solvent, the latter being dichloromethane or chloroform, with boiling points of 40 and 60 ° C, respectively. Subsequently, these two solutions were mixed in the presence of magnetic stirring, thus constituting the organic phase. The preparation of the aqueous phase and the subsequent synthesis process are identical to that described in Example 1.

Example 5. Preparation of the capsules of Example 4 with different photochromes The same method used in Example 4 was used for encapsulation of other types of photochromic, all commercially available. These can be divided into two families: spiropiranos and spiroxacinas. As regards the first family, the following photochromes were encapsulated separately: 1 ', 3', 3'-trimethylspiro [1 (2H)

5

10

fifteen

twenty

25

30

35

benzopyran-2,2'-indoline], 8-methoxy-1 ', 3', 3'-trimethylspiro [1 (2H) - benzopyran-2,2'-indoline] and 1 ', 3', 3'-trimethyl -6-nitrospiro [1 (2H) -benzopyran-2,2'-indoline]. Regarding the second family, they were encapsulated: 1,3,3-trimethylspiro [2H-indole2.3 '- [3H] naphth [2,1- b] [1,4] oxacin], 1,3,3 -trimethylspiro [2H-indole-2,3 '- [3H] phenanthro [9,10-b] (1,4) oxacin] and two photochromes of commercial name, Reversacol® Athlantic Blue and Velvet Blue.

Example 6. Preparation of a film of polymeric material with nonanoic acid capsules and photochromic properties obtained in Examples 4 and 5, in accordance with the present invention.

The capsules obtained in Examples 4 and 5 were dispersed (80 mg) in 7 mL of an aqueous solution, in which 1.4 grams of polyvinyl alcohol (20% aqueous PVA solution) had previously dissolved. The suspension was stirred by ultrasound to achieve a homogeneous dispersion. Subsequently, it was deposited in a polystyrene petri dish (4.5 cm in diameter) and the water was evaporated, at room temperature, until the polymer was completely dried by trapping the micro / nanocapsules in its structure.

The film obtained, at room temperature, is colored, and when irradiated with visible light a discoloration of the system (from magenta to white) is observed, on the surface that has been subjected to radiation (reverse photochromism).

In this way, this film can be initially colored, so that when it is subjected to solar radiation (containing visible light and ultraviolet radiation) it is completely discolored. During the day the film is colorless, while at night it shows color and lowering its transmittance.

This film can also be irradiated with a laser pointer, with which an image or text is drawn. The image or text is generated by discoloration of the part of the film that is irradiated. The generated image or text remains for a certain period of time (some minutes). By heating the film or subjecting it to ultraviolet radiation the discolored part is re-colored and the image or text can be erased.

Example 7. Preparation of the capsules with PES, dodecanoic acid and 1'- (2- hydroxyethyl) -3'.3'-dimethyl-6-nitrosDiro [1 (2H) -benzopyran-2.2'-indolinal properties with properties

thermo-photochromic according to the present invention

5

10

fifteen

twenty

25

30

35

For the preparation of the capsules, the same method used in Example 1 was used. In this particular case, for the preparation of the organic phase, a small amount of the photochrome in question (30mg) was dissolved in 883 mg of dodecanoic acid ( acid phase change material), at a temperature above its melting point (43 ° C), in the presence of magnetic stirring at 1500 rpm. Then, 500 mg of polysulfone was dissolved in 10.4 mL of a volatile organic solvent, the latter being dichloromethane or chloroform, with boiling points of 40 and 60 ° C, respectively. Subsequently, these two solutions were mixed in the presence of magnetic stirring, thus constituting the organic phase. The preparation of the aqueous phase and the subsequent synthesis process are identical to that described in Example 1.

Example 8. Preparation of the capsules with octadecyl phosphonic acid and the photochrome 1 '- (2-hydroxyethyl) -3', 3'-dimethyl-6-nitrospiro [1 (2H) -benzopyran-2,2'-indolinal with properties thermo-photochromic according to the present invention

For the preparation of the capsules, the same method used in Example 1 was used. In this particular case, for the preparation of the organic phase, a small amount of the photochrome in question (30mg) was dissolved in 1 g of octadecyl phosphonic acid. (acid phase change material), at a temperature above its melting point (95 ° C), in the presence of magnetic stirring at 1500 rpm. Then, 500 mg of polysulfone was dissolved in 10.4 mL of a volatile organic solvent, the latter being dichloromethane or chloroform, with boiling points of 40 and 60 ° C, respectively. Polysulfone has been selected for its higher thermal resistance than polymethylmethacrylate, since the capsules have to resist up to the melting temperature of the acid medium (95 ° C). Subsequently, these two solutions were mixed in the presence of magnetic stirring, thus constituting the organic phase. The preparation of the aqueous phase and the subsequent synthesis process are identical to that described in Example 1.

Example 9. Preparation of a film of polymeric material with octadecyl phosphonic acid capsules and thermo-photochromic properties obtained in Example 8 according to the present invention

The capsules obtained in the previous example were dispersed (30 mg) in 7 mL of an aqueous solution, in which 1.4 grams of polyvinyl alcohol (20% PVA solution) had previously dissolved. The suspension was stirred by ultrasound to achieve a homogeneous dispersion. Subsequently, it was deposited on a plate of

polystyrene petri (4.5 cm in diameter) and the water was evaporated, at room temperature, until the polymer was completely dried trapping the micro / nanocapsules in its structure.

5 The film obtained, below 95 ° C, is discolored, and when irradiated with UV light a color change (from white to violet) is observed, on the surface that has remained in contact with the radiation. Above 95 ° C, the film is colored (reddish color) and when irradiated with visible light it fades, recovering its initial color when left in the dark.

10

Claims (18)

5 10 fifteen twenty 25 30 35 1. A film of polymeric material with thermo-photochromic properties characterized in that it comprises capsules of micrometric and / or nanometric size embedded and deposited homogeneously dispersed in its structure, said capsules being formed by a solid wall of a polymer different from the polymer of the film that contains in its interior a dispersion of at least one photochromic compound of the T-type that is selected within the group consisting of spiropyranos, spiroxacin, chromenes and any combination thereof, in an acid-type liquid phase change material non-volatile that interacts with the photochrome as a function of temperature. 2. The film of claim 1, wherein the micrometric capsules have an average size between 101 nm and 1000 microns, including both limits, and the nanometric capsules have an average size between 10 and 100 nanometers, including both limits. 3. The film according to any of claims 1 or 2, wherein the polymeric material of the film is selected from the group consisting of polyvinyl alcohol, polyvinyl pyrrolidone, ethyl cellulose, polymethylmethacrylate, polystyrene, acrylic, styrenic, polyurethane, polyurea and polyamide. 4. The film according to any of claims 1 to 3, wherein the solid wall of the capsules is of a polymer selected from the group consisting of an organic polymer or an inorganic polymer. 5. The film according to claim 4, wherein the solid wall polymer of the capsules is selected from the group consisting of polymethyl methacrylate, polystyrene, polysulfones, polyamines, polyureas and polyurethanes, when it is an organic polymer; and silica gel, when it is an inorganic polymer. 6. The film according to any one of claims 1 to 5, wherein the photochromic compound of the spiropyran family is selected from the group consisting of 1 '- (2-hydroxyethyl) -3', 3'-dimethyl-6-nitro -spiro [1 (2H) - benzopyran-2,2'-indoline], 1 ', 3', 3'-Trimethyl-6-nitrospiro [1 (2H) - benzopyran-2,2'-indoline], 1 ' , 3 ', 3'-Trimethylspiro [1 (2H) - 5 10 fifteen twenty 25 30 35 benzopyran-2,2'-indoline] and 8-Methoxy-1 ', 3', 3'-trimetillspiro [1 (2H) -benzopyran-2,2'-indoline]; and the photochromic compound of the spiroxacin family is selected from 1,3,3-trimethylspiro [2H-indole2,3 '- [3H] naphtho [2,1-b] [1,4] oxacin] and 1,3 , 3-trimethylspiro [2H- indole-2,3 '- [3H] phenanthro [9,10-b] (1,4) oxacin]. 7. The film according to any one of claims 1 to 6, wherein the non-volatile acid phase change liquid material is selected from the group consisting of: an aliphatic carboxylic acid with a carbon number greater than 7, a phosphonic acid selected from the group consisting of decyl phosphonic alcohol, dodecyl phosphonic, hexadecyl phosphonic and octadecyl phosphonic; a phenol; a non-volatile alcohol with a carbon number greater than 8 and a polyalkylsiloxane with hydroxyl terminations. 8. The film according to claim 7, wherein the acid-type liquid phase change solvent has a melting point between -15 ° C and 95 ° C. 9. The film according to claim 8, wherein the acid-type liquid phase change solvent has a melting point lower than room temperature. 10. The film according to claim 9, wherein the acid-type liquid phase change solvent is nonanoic acid, with a melting point of 13 ° C. 11. The film according to claim 8, wherein the acid-type liquid phase change solvent exhibits a melting point greater than room temperature. 12. The film according to claim 11, wherein the acid-type liquid phase change solvent is dodecanoic acid, with a melting point of 43 ° C. 13. The film according to any one of claims 1 to 12, comprising a protective film on one of its two faces, of a material selected from the group consisting of acrylic, styrenic, polyamide, polyurethane and glass. 14. A laminar surface of glass or plastic material characterized in that it comprises the film described in any one of claims 1 to 13 adhered to one of its faces. 15. A laminar surface of glass or plastic material characterized in that it comprises the film described in any one of claims 1 to 12 adhered to one of its faces and comprising a second laminar surface, of the same or different material as the first surface, adhered to the other side of the movie, so that 5 This is comprised between the two laminar surfaces. 16. The laminar surface described in any one of claims 1 to 15, which is selected within the group consisting of: a showcase, a window, a blackboard, a chromic screen and a protective screen of objects. 10 17. A device characterized in that it comprises the film described in any one of claims 1 to 13 adhered to all or part of its external surface. 18. The device described in the preceding claim, which is selected within the group consisting of: textile products, advertising signs, traffic signs, vehicle body, food product packaging; bottles, cans and tetra bricks; memory and / or recording devices and / or deletion of data and documents and bills.